This invention relates generally to vehicles including a turbofan engine and, more particularly, to methods and systems for supplying air to the vehicle.
At least some known military air mobility systems use air from a propulsion system to enhance the operational characteristics of high lift devices on the vehicle. In such systems, the air source must provide a sufficient quantity of air at moderate pressures and temperatures. Moreover, the quantity of air must be easily modulated from its maximum levels to zero flow, as air flow at maximum levels is utilized under high lift conditions and zero air flow is utilized under forward flight conditions.
At least some known propulsion systems use air systems that provide only low pressure air. Specifically, these known systems channel low pressure air from a fan assembly in the engine. Because of the relatively low pressure of the air, these known propulsion systems generally require a large quantity of air resulting in the need for relatively large air systems to pass the low pressure air. Other known systems that channel air from high pressure compressor at higher pressures and temperatures than desired. Specifically, these systems channel air from various stages of the compressor. Generally, both the compressor and the air system require modulation of the air quantity to affect a transition between the modes of operation for the compressor and the air system. As a result of the modulation, air flow and pressure to the engine system turbine is decreased. Accordingly, engine performance is altered. Further, costly components are often required because of the higher temperature air.